my afr falls from 11.0@4k to 10.3@the top
much gain to be had from leaning up?

 

Definitely. Depending on how aggressive your timing map is, you may need to dial back a degree or two when you take out that much fuel, but it will net you gains upwards of 20whp

 

ok thx

 

20whp from just changing fueling from 10.5 to 11.5 afr? Is that what you are saying?

 

it will save you some gas. and in my experience the car will feel better.

depending on the afr I have seen 5 mpg up to 8 mpg on a race track. the 8 might be responsible for the new motor though.

 

there is actually no definite answer... it's here in Reno I can tune for 11.5 but I don't gain any power going from 11.1 to 11.5.. even with adjusting timing. so you might be able to lean it out some and add 5- 10 whp but 20 is a considerable amount. just my .02

 

anything under 11 will lose power unless its spraying methanol at the same time. 11.0-11.5 is about a draw, but a little leaner starts to pick up a little power. I wouldnt quite say 20whp, but 10whp definitely.

 

Leaner is meaner as long as the EGT is under control.

What is the octane?

 

Thats old school i like that!

whats next " If you aint knocking you aint rocking"

its the UK so it cant be much oct

 

Typically 98RON is 92.5R+M/2 USA method.

 

when i was in germany, might as well put moon shine in my silvia but yes in kindda 93

 

uk vpower which is iirc 98ron? uk spec

 

UK Shell V-Power is 99RON according to Shells website.

 

yep, vpower is 99ron (sure it says on pump)

we also have tesco99

and bp 102 (but that is way too expensive)